There are different applications in the aeronautic industry in which a deployable propeller is foreseen, like Emergency Ram Air Turbines in commercial airplanes or self-motorized gliders. In commercial aircraft, an Emergency Ram Air Turbine is a system that allows getting power from external airstream in a multiple engine failure case deploying a propeller device from, usually, a dedicated fairing or pod. In the case of gliders, in order to avoid dependency from another engine powered aircraft for take-off, some solutions to deploy and/or to fold again the propeller in flight are known.
There are also applications in watercraft where a deployed propeller is desirable as for minimizing water drag in wing sailing boats and others.
In all the cases, the propeller needs to remain folded and hidden while it is not needed, in order to minimize the drag, and it is unfolded or deployed when required to allow for thrust.
Known solutions for folding and unfolding a propeller are described in U.S. Pat. No. 2,021,481 “Folding Propeller,” U.S. Pat. No. 2,198,475 “Collapsible Propeller for Airplanes,” U.S. Pat. No. 2,500,382 “Folding Propeller” and U.S. Pat. No. 6,152,693 “A Folding Propeller” dedicated to vessels and sailing ships.
U.S. Pat. No. 2,848,054 “Aeronautical Propeller Spinner” describes a ventilation system inside the spinner of a propeller device.
U.S. Pat. No. 7,886,544 B2 “Propeller or Propeller Drive” describes both propeller drives and folding propeller methods.
However, there are not known propeller devices for aircraft, spacecraft or watercraft able to deploy or retract the blades while moving in flight or water.